I used to work with ArcGIS. There I had geodatabases in which I could store several shapefiles with defined layer styles.

Is there a way to do something similar with QGIS?

The background is: we are a team of 5-10 people, and would like to save all of our spatial data in one database, so that we can use them in different QGIS projects on several workstations, and when someone changes something it will be automatically updated in all projects. Before I started here, we had many different "local" shapes, and sometimes changes would effect other peoples' work without them getting to know the changes.

Also it was quite comfortable that in ArcGIS you could just add a geodatabase to a project and then have dozens of shapes inserted at once, with defined layer styles.
At the moment we are saving our shapefiles on a hard disk in our network, and have to add the shapes manually to our projects, but then we have to sort the shapes in different folders and adjust the layer styles manually every time..

Besides the styles "solution", if your team works with a server, then you might consider installing Postgres\Posgis to keep all your data. Where I work, it gave us a nice access performance when compared with reading from shapefiles, along with all the SQL analysis that you can do with it.
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Alexandre NetoFeb 7 '13 at 14:57

no grammar mistakes found in a quick read ;) you are doing ok sir :)
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dbzaNov 28 '14 at 23:07

In Addtion to saving defined layer styles within project files on the network, you can create a single Spatialite enabled database.sqlite, if your workflow isn't too busy.

For myself, I've replicated a fgdb by importing a hundred shapefiles and a couple hundred datatables, with great performance. Spatialite won't allow for PostGIS or FileGDB style mutli-user editing across the network, but you can easily export layers from it, then when finished import it back. Create a shared spreadsheet that tracks who's working on which layer. The advantage is that project can have a single file (not a whole directory) that's easily emailed, backed up, etc. Read the quote below from SQLite FAQ before proceeding..

"
Multiple processes can have the same database open at the same time. Multiple processes can be doing a SELECT at the same time. But only one process can be making changes to the database at any moment in time, however.

SQLite uses reader/writer locks to control access to the database. (Under Win95/98/ME which lacks support for reader/writer locks, a probabilistic simulation is used instead.) But use caution: this locking mechanism might not work correctly if the database file is kept on an NFS filesystem. This is because fcntl() file locking is broken on many NFS implementations. You should avoid putting SQLite database files on NFS if multiple processes might try to access the file at the same time. On Windows, Microsoft's documentation says that locking may not work under FAT filesystems if you are not running the Share.exe daemon. People who have a lot of experience with Windows tell me that file locking of network files is very buggy and is not dependable. If what they say is true, sharing an SQLite database between two or more Windows machines might cause unexpected problems.
" -- http://www.sqlite.org/faq.html#q5